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Tweak 4-way parallel output to work on pins 12-15 on esp8266 - keep b…

…locked out for now, needs some more testing.
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focalintent committed May 22, 2016
1 parent a448d5c commit 20e5042e9f868c0c56ce08571e0cc3344af9e8f4
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  1. +28 −0 bitswap.cpp
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+#define FASTLED_INTERNAL
+#include "FastLED.h"
+
+/// Simplified form of bits rotating function. Based on code found here - http://www.hackersdelight.org/hdcodetxt/transpose8.c.txt - rotating
+/// data into LSB for a faster write (the code using this data can happily walk the array backwards)
+void transpose8x1_noinline(unsigned char *A, unsigned char *B) {
+ uint32_t x, y, t;
+
+ // Load the array and pack it into x and y.
+ y = *(unsigned int*)(A);
+ x = *(unsigned int*)(A+4);
+
+ // pre-transform x
+ t = (x ^ (x >> 7)) & 0x00AA00AA; x = x ^ t ^ (t << 7);
+ t = (x ^ (x >>14)) & 0x0000CCCC; x = x ^ t ^ (t <<14);
+
+ // pre-transform y
+ t = (y ^ (y >> 7)) & 0x00AA00AA; y = y ^ t ^ (t << 7);
+ t = (y ^ (y >>14)) & 0x0000CCCC; y = y ^ t ^ (t <<14);
+
+ // final transform
+ t = (x & 0xF0F0F0F0) | ((y >> 4) & 0x0F0F0F0F);
+ y = ((x << 4) & 0xF0F0F0F0) | (y & 0x0F0F0F0F);
+ x = t;
+
+ *((uint32_t*)B) = y;
+ *((uint32_t*)(B+4)) = x;
+}

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